DETERMINATION OF THE BASIC PARAMETERS OF PSEUDOMORPHIC GAINAS QUANTUM-WELLS BY MEANS OF SIMULTANEOUS TRANSPORT AND OPTICAL INVESTIGATIONS

Combined studies of GaAlAs/GaInAs/GaAs pseudomorphic structures have b een performed by means of transport under hydrostatic pressure, lumine scence and cyclotron resonance emission experiments. The structures in vestigated were 130 angstrom quantum wells. They were delta-doped outs ie of the quantum well, with the spacer thickness ranging between 20 a nd 60 angstrom. These structures allowed us to study the influence of the carrier density, N(s) on mobility and on the position of the Fermi level E(F) above the first electrical sub-band E0. By using pressure and illumination, we changed N(s) from 0.5 to 1.8 x 10(12) cm-2. In th is range, only the first electric sub-band is populated. A strong decr ease of mobility at higher concentrations was shown and dependent esse ntially on correlation effects. High magnetic field transport measurem ents confirmed that only the lowest sub-band was populated. Moreover, cyclotron resonance emission gave the effective mass as a function of the carrier density in the well. On this basis, the importance of the non parabolicity effect was estimated. All these results were interpre ted within the framework of the variational method leading to a determ ination of the most important physical parameters describing this syst em.